The purpose of this protocol is to establish the qualitative and quantitative toxicity of bryostatin 1 when administered to children whose cancer is refractory to standard therapy. This study will determine dose-limiting toxicities, establish a maximum tolerated dose and obtain pharmacokinetic data. This study will provide information to determine which clinical and laboratory studies are needed to monitor or alter therapy with this agent and to determine precautions and supportive therapy that should be used. New protocol.